Having trouble with welding thin tube

admin

I am creating frames out of 1 1/4" square tube, .063 thickness.  I'm having a hard time MIG welding the corners without blasting through the metal.  The corners are mitered with small gaps.  I have turned down the settings to 20 Volts, and a wirespeed of around 4.   I can kind of get this to work.  I am using a crescent motion.   I try to move faster and wider as I go but I end up blasting through as I reach the end of the weld.  The welder sputters and hisses when turned down this low and doesn't sound right.  Any advice?Here's a picture of a weld.
Reply:I guess the picture is too big...here's a link:http://share.shutterfly.com/osi.jsp?i=EeANXLdyzbs2bHPA
Reply:Do you plan on grinding aferwards?  If so, and since it's a Mig, with gas I would assume.  Reset your speed and voltage so that your wire isn't "Popping" Then take a short pass, and stop,  What I mean by this is... Work the wire from one side into the middle, and up onto the other side.  Then stop.  From the looks of your picture, I'd say you tried that.  If you make one pass at it, then let the weld cool,  slightly You don't have to move, just let go of the trigger.  As you see (through your helmet) the red glow disappear, take another swipe at it.  Stop again.  Keep doing this as you work your way along the gap.  Make sure that you push the wire into your first pass each time.  You will slowly build up and along the gap as you go.        I'm sure there IS a better way to do this, but from my experiences with thin stuff, that has always worked for me.  You will require grinding when finshed as this method tends to build the bead up higher than is usually desired.  This does not work as well if you are using a flux core wire.  Just my 2 cent worth.... and that's a Canadian 2 cents, which would only be about a half a penny U.S.  Packrat.Lincoln 225 AC/DC, Hobart 140 Mig. Oxy/propane Victor torch.(2) Makita 5" angle grinders  one with zip disk, 14" chop saw.  and just about every other tool you can think of. Whoever has the most toys when he die's ..... Wins!
Reply:That makes sense, Packrat.  Yes I'm using gas.  Sounds like I need a little patience to do the single pass technique.  I'd prefer not to grind the weld if I can get away with it. This project is a gate on a deer fence out in a field where no one but me will see the crappy welds.  So a little bumpy is okay, but I have been grinding the messes I have been making earlier.  I'll give it a shot, thanks.  Is it possible to weld without sputtering and hissing at low, low voltage/wire speed settings or are those settings for .22 wire?  (I'm using .35 wire)
Reply:Looking at the photo, I would either trigger it in or try to run it downhand.Common sense in an uncommon degree is what the world calls wisdom.
Reply:By "trigger it in", do you mean what Packrat is referring to?I'll give both methods a try, although the downhand method is a little inconvenient (3' by 6 1/2' frame) it is do-able.
Reply:To trigger in the weld is to basically overlap tacks down what you are wanting to be welded.  In production welding, sometimes you run so hot that you have to do it that way otherwise you have to go set your machine differently for each weld.Common sense in an uncommon degree is what the world calls wisdom.
Reply:It looks to me like you are running in the wrong direction.  When you start a weld the material is cold and you always have a high bead at the start.  Since the outside corner needs less heat that is where you should start.  When you reach the inside corner your bead is hot.  There are more directions for your weld heat to travel so you can take advantage of the heat buildup in your bead.  This tactic will not solve all your problems but should reduce them.
Reply:This is all great information, thanks.    Geez, it didn't even occur to me to travel from the outside corner to the inside corner.  That totally makes sense.   There should be a lot less cursing on the next frame I build.
Reply:With the MIG, it also gets hotter if you push the weld instead of pulling it...  You might experiment a bit with that.Hey! Bring the camera...Is it still hot?   $%#^%^#  Guess so...
Reply:I was pulling on these welds and they still burned through.  Touchy stuff, this thin metal welding.  Keeps me from getting cocky, that's for sure.
Reply:Hey Brainfarth, I tried the 'trigger in' method of multiple spot welds and it worked.  It wasn't pretty but I wasn't concerned with it how it looked.  When using the trigger in method, do you start at one end and work your way across?  I alternated ends which probably explains why it looks a little sloppy.